1. Field of the Invention
The present invention relates to a vehicle headlamp and more particularly to a vehicle headlamp that uses a discharge bulb as a light source and has a lighting circuit.
2. Prior Art
One type of vehicle headlamp uses a discharge bulb as a light source.
Such a vehicular headlamp requires a ballast circuit and a starting circuit so as to light the discharge bulb. The ballast circuit increases the voltage of a battery installed in the vehicle and converts the battery voltage to a corresponding AC voltage and applies it to the discharge bulb. The starting circuit applies a high starting voltage required for the start of lighting. Generally, the ballast circuit and the starting circuit are installed in a casing, thus forming a lighting circuit assembly; and this lighting circuit assembly is integrally mounted on the headlamp.
FIG. 6 shows one example of this headlamp. A reflector c is provided in a space defined by a lamp body a and a front cover b that covers the front opening of the lamp body a. The reflector c holds a discharge bulb d. A disposition recess g for housing a lighting circuit assembly f is provided at the bottom of the lamp body a, and the lighting circuit assembly f is installed in the disposition recess g. A power feeding connector i connected to the lighting circuit assembly f by a cord h is connected to a connector portion (not shown) of the discharge bulb d.
In some cases, however, a lamp body has no space for the lighting circuit assembly in the bottom. In this case, the lighting circuit assembly is disposed on the outer side surface of the lamp body. If the lighting circuit assembly f is disposed in the bottom of the lamp body a as shown in FIG. 6, the disposition recess g is formed by way of slightly protruding the bottom wall of the lamp body a downward. Therefore, there is no problem with the strength required for supporting the heavy lighting circuit assembly f. However, if the lighting circuit case for housing the lighting circuit assembly needs to be disposed on the side of the lamp body, the lighting circuit case and the side or the rear portion of the lamp body are connected by some form of connection means. As a result, the strength of the connection means becomes the issue.
When the discharge bulb or the lighting circuit assembly is need to be replaced, it is necessary to remove the power feeding connector from the discharge bulb or remove the lighting circuit assembly from the lamp body. In such cases, it is necessary to avoid the power feeding connector and the cord that connects the power feeding connector to the lighting circuit assembly from being caught between the reflector and the lamp body. As a result, a passage for the power feeding connector and the cord is required between a discharge bulb-supporting portion of the reflector and the lighting circuit case. Generally, the lighting circuit assembly, the cord, and the power feeding connector are formed integrally, and they are structured in a mutually inseparable fashion so as to ensure the safety. As a result, when the lighting circuit assembly is to be removed from the lamp body, it is necessary to pull out the power feeding connector. In such a case, chances are that the power feeding connector is caught between the reflector and the lamp body.
Accordingly, it is an object of the present invention to provide a vehicular lamp that supports a lighting circuit assembly on a side of a lamp body without presenting any problem with strength.
Another object of the present invention is to provide a vehicular lamp that has a passage for a power feeding connector and a cord that connects the power feeding connector to a lighting circuit assembly.
The above objects are accomplished by a unique structure for a vehicle headlamp that comprises: a lamp body, a front cover that covers the front opening of the lamp body, a reflector disposed in a space defined by the lamp body and the front cover, a discharge bulb supported by the reflector, a lighting circuit assembly that includes in a casing a ballast circuit for lighting the discharge bulb and a starting circuit; and in the present invention,
a lighting circuit case that houses the lighting circuit assembly is integrally disposed on the lamp body with a connecting portion in between and is provided on the side of the lamp body; and
the connecting portion is in a shape of a lateral U in vertical cross-section so as to allow the power feeding connector to pass through.
In the vehicle headlamp according to the present invention, the connecting portion that integrally connects the lighting circuit case to the lamp body has nearly a lateral U-shape in vertical cross section. Accordingly, the connecting portion has a great strength due to its shape. Thus, when a heavy lighting circuit assembly is housed in the lighting circuit case, the weight is sufficiently supported, and the connecting portion is prevented from being changed its shape.
In addition, the connecting portion is of a lateral U-shape in vertical cross section. As a result, a sufficient space is obtained in the connecting portion, and the connecting portion functions as a passage for the power feeding connector. When the lighting circuit assembly is removed from the lamp body, the power feeding connector will not be caught between the reflector and the lamp body.